Thursday, September 29, 2011

Consumed by Wood

We have lots of wood around here, and some of it naturally makes it into the marine environment, delivered by flooding rivers and eroding banks. And then sometimes we help it along. Many harbors in the Puget Sound region are finding that they are "polluted" with wood waste. Decades of log rafting and storage in the quiet corners of the Salish Sea coated the bottom with logs, bark, twigs and wood fragments that can be meters thick.

Yesterday I had the opportunity to dive a site slated for a shoreline restoration by the Lower Elwha Klallam Tribe. Its an old log loading ramp - a place where trucks could drive over the water and dump their logs. Here is the site as it looked in 1990:

and here it is in 2009, after most of the over-water structure had been removed by the WA DNR:

Two things struck us as we descended to 60 feet under the surface that historically supported vasts rafts of logs. First, there wasn't a lot living in this environment. In particular, I was struck by the lack of shellfish. There were a few small Dungeness crab, a few monster Red Rock crab, and a Short-Spined sea stars (Pisaster brevispinus). Once we moved out of the major impact area I also spotted a large California cucumber (Parastichopus). In deeper water on some of the logs there were larger Metridium anenomes. But in the substrate itself - nothing that I could detect. No clams, no tube-worms, no amphipods.

Next, that there was an impressive amount of wood waste on the bottom. I could stick my entire arm into the bottom, up to my shoulder, and feel only bark and twigs. Even after being out of commission for 20+ years, there wasn't much sediment deposited on top of this waste. I suspect that the lack of shellfish and other life in the substrate is because there was no substrate - just wood.

We found many old log tags, some marked with the company name, "ITT Rayonier"

A giant Metridium. This one was almost almost a meter high.

One of those big Red Rocks, somehow getting big with nothing to eat? Look at the substrate - the pieces that look like big cornflakes? Those are big chunks of bark covering the bottom.

Big raft chain

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